The glass jelly travels slowly along dungeon corridors and cave floors, absorbing carrion, creatures, and trash. Inorganic material remains trapped and visible inside the jelly’s body. Glass jellies are huge, averaging 1,000 cubic feet and weighing as much as 20,000 pounds. The body of a glass jelly is more viscous than that of other jellies, and it tends to take on the shape of its surroundings such that one in a dungeon with 10’ wide corridors might have a shape similar to that of a cube, while one living in round sewer drains under a city would have a cylindrical or half-cylindrical shape.

If a glass jelly encounters a narrow place (a doorway, for example) it will need 2d4 rounds to push through the constriction and will have assumed a new shape after doing so; such a new shape will persist for twice as long as it took to pass the constriction before the monster begins to flow into a shape that fills the available space again.

Glass jellies move quietly, making a faint sucking or slurping sound if anyone thinks to listen. Combined with their transparency, they are able to surprise prey on a roll of 1-3 on 1d6. Worse, any living creature hit by a glass jelly must save vs. Paralysis or be paralyzed for 2d4 turns in addition to suffering damage from its acid secretions.

Any treasure indicated will be visible inside the creature, which must be slain if the treasure is to be recovered.